Speed governor for motors



1954 c. H. SPARKLIN SPEED GOVERNOR FOR MOTORS 67ZQ7/66 W huh OriginalFiled Oct. 31, 1946 Nov. 30, 1954 c. H. SPARKLIN SPEED GOVERNOR FORMOTORS 2 Sheets-Sheet 2 Original Filed Oct. 51, 1946 m5 m 1 a o a Q as?W W United States Patent SPEED GOVERNOR FOR MOTORS Charles-'H.Sparklirr, Chicago, 111., assignor to Birtman Electric Company, acOr-porationof' Illinois- Griginalapplication- 0ct'oher31, 1946, SerialNo. 707,014, new Patent No- 2,541,120, dated'February 13, 195.1. Dividedand this applicati'On'May 16, 1950, Serial No. 162,172

3' Claims. (Cl; 200-80) This. inventionarelates to a speed governor foraimotor, and particularly to such a. governor including means. forventilating the parts thereof.

This application is a: division of my copending application Serial No.707,014; filed October 31, 1946, now U. S. Patent 2,541,120 issuedFebruary 13, 1951.

Many speed governors for regulating. the. speed of electric motorsinclude make-and-break contact switches for regulating the current flow101.1116. motor. As these switches alternately open and. close rapidly,considerable heat is generated in the. switch; This heat can causedamage to the contact points unless it is removed.

The motor governor of. this. invention includes'ventilating means forefficiently ventilating the governor switch and. associated. parts andfor simultaneously ventilating the other portions of themotor. Theventilating means is not only efficient, but is quite simple andinexpensive to construct as in the preferred construction arotatablepart of the governor is employed as a. portion of the ventilating, fanand a. part of the motor casing. is used to concentrate the air flowthrough the. fanand across the governor including those portions thatare subject to the highest heat development, including. the contactpoints of the switch.

The invention will be described as relatedto. theembodiment set out inthe accompanyingdrawings; Of the drawings, Fig. 1 is a. longitudinalvertical section taken through the motor assembly along the line 11 ofFig. 2; Fig. 2 is a horizontal section taken along line: 22 of Fig; 1';Fig 3 is a section taken along. line 33 of Fig. 1; and Fig. 4 is asection taken along line 44 of Fig. 1.

The embodiment shown in the drawings is a food mixer motor comprising anarmature 10, a surrounding field coil 11, a commutator 12, a motor shaft13 upon which the armature and commutator are mounted, a main casing 14surrounding the motor, a first casing section 15 at the front of themotor assembly, and a second casing section 16 at the rear of the motorassembly. The second casing section is rotatably mounted on a pedestal17 by means of a hinge pin 18.

The front end of the motor shaft 13 extends through a wall 19 separatingthe main casing 14 from the first casing section 15. The motor shaft isheld in a bearing 20 in this wall and the end of the shaft extendinginto the first casing section 15 is formed as a worm gear 21.

The worm gear 21 engages a horizontal gear wheel 22 keyed to a secondworm gear 23 held in vertical position between a bottom bearing 24 and atop bearing 25 with these bearings forming part of the first casingsection 15. Both bearings 24 and 25 have annular cross sections so thattools may be inserted in the openings formed and engage either thebottom or top ends of the worm gear 23. As shown in Fig. l, the bottomend of the worm gear 23 is connected to an agitator 26 having a beaterportion 27. The top end of the worm gear is formed with a notch 28 towhich tools such as juice extractors may be attached.

The second worm gear 23 engages a second gear wheel 29 arrangedvertically and transverse to the motor assembly. This second gear wheel29 is concentric with a socket 30 that is mounted on the wall 19 bymeans of a rear portion 31 extending through the wall until held inplace by a boss 32 on the other side of the wall 19. The front of thesocket 30 communicates with an opening at the front of the first casing15, through which the shafts of power tools may be inserted to engagethe slot 33 in a smaller shaft 70.

From; the above description it can be seen that the second worm gear 23and; attached gear wheel 22' are mounted on the first casing section 15and that the second gear wheel 29 and socket 30 are mounted on the wall19; The wall 19 is separable from the motor casing 14 and is held inplace by a plurality of bolts 34. The first casing section: 15' is heldin place by a plurality of bolts 35 having their heads in. recesses 36at the. front of the first casing section 15. This casing section. isalso provided with a handle 37 on its topsurface.

At the rear of the motor casing 14 therev is located"v a wall 38-through which the other end of the motor shaft 131 extends, with. thisend being. held in a bearing 39. This wall is made integral with. themotor casing 14, although; it may be made separable if desired. The rearof the motor casing 14 contains thickened portions 40 in which aremounted the motor brushes 41.

The speed control means for the motor is: mounted with-in the. secondcasing section 16. The speed governor comprises two parallel plates 42mounted for rotation on the rear end of the shaft 13, with the platesheld in spaced-apart relationship. On the back of the inner plate 42there is mounted a plurality of radial blades 71 that extendv beyond theperiphery of the inner plate. These blades act as a fan and set up acirculation of air through the motor when the motor is in. operation.The air enters spaced holes 72 at the opposite end. of the motor casing14 and is drawn around the motor, through openings 74- in the wall'38,around the fan, and out rear openings 75 in: the casing section 16.

Between the rotatable plates 42 are located a pair of centrifugallyresponsive arms 43 hingedly mounted at one end of eachv arm and arrangedto be swung ontwardly by centrifugal forces acting on the arms. Thesearms. press against bell cranks 44 hingedly mounted on fulcrurns 45-.The other end of each bell crank 44 bears against. one arm of a secondbell crank. 46 arranged at right angles to the rotatable plates 42. Theother arms of these bell cranks 46 extend toward the motor shaft 13 and.bear against a rotatable thimble 47 mounted on the end of the shaft 13.Thus, by increasing rotation of the. motor armature the thimble 47 ismoved farther out from the. rotatable plates 42, and this distance. isdependent upon. the speed of rotation of the. motor.

Inv order to limit the speed to any predetermined value there areprovided two contact arms 48 and 49, arranged substantially parallel toeach other and transverse to the motor shaft 13. These contact arms aremounted on short arms 77 hingedly mounted on the second casing section16 as by a hinge pin 50. The other ends of the contact arms carryelectrical contacts 51. The thimble 47 extends through an opening 53 inthe nearer contact arm 58 and presses against a button 54 on the farthercontact arm 49. The nearer short arm 77 has an extended portion 55engaging a groove 56 in a vertical threaded bolt 58 extending throughthe top of the casing section 16. The top of this bolt is provided witha cap 59 that may be grasped by the fingers in order to rotate the bolt58. The contact points 51 are normally held in contact by first spring60 extending around the hinge pin 50 and bearing against both contactarms 48 and 49. Thus the points 51 are held in contact until the speedof rotation causes the thimble 47 to move the arm 49 away from arm 48against the urging of spring 60. This breaks the electrical connectionto the motor, and the speed slows down until the points 51 again come inconact. The speed may be varied by turning the cap 59 to .iove thecontact arms 48 and 49 toward and away from the motor shaft. In atypical installation, the speed range of the speed control isapproximately 6 to 1. By providing a second spring 61 extending betweenthe rear of the casing section 16 and the rear portion of the contactarm 49 this speed range may be almost doubled. This type speed governor,its construction, and operation are shown in greater detail in mycopending application Serial No. 580,114, filed February 28, 1945.

The contact arms 48 and 49 are preferably made of aluminum, copper,brass or other heat-conducting metal. The contact points 51 are eachmounted directly on an arm while each arm is insulated at its base byblocks of insulation 76. The contact arms may or may not be providedwith spaced holes to improve the cooling effect of the cooling air.

Each contact point 51 has a head 78 made of tungsten mounted on a bronzebase 79 which in turn is fastened to a contact arm. The particulartungsten used in one installation was Grade F tungsten made by the H. A.Wilson Co. of Newark, N. J. Each tungsten head was about to inch thickand about inch in diameter. These contacts were used for over 1,000hours without any pitting of the surfaces of the contacts.

The cooling air that is circulated through the motor by fan blades 71 isdirected across the contact arms 48 and 49 and the contact points 51.This may be accomplished by locating the exit openings 75 adjacent thecontact arms, by properly shaping the casing, by providing baffles, orby any combination of these. As illustrated in Figs. 1 and 2 theconcentration of air is accomplished both by shaping the casing section16 and by locating the air exit holes 75 adjacent the contact arms andpoints.

In the ordinary installations of the speed governor a condenser isprovided across the contact points to reduce sparking, and a secondcondenser is also preferably provided in the electric line.

The casing for the motor and for the speed governor may be made of anymaterial, but is preferably a light weight metal such as aluminum.

As can be seen from the above description, the contact arms 48 and 49,the springs 60 and 61, the threaded bolt 58, and the cap 59 are mountedon the second casing section 16, and the assembly may be removed as aunit. The second casing section is normally held in position by means ofa plurality of bolts 62.

The button 54 that is mounted on contact arm 49 is insulated from thisarm, and the spring 61 is also insulated from arm 49.

Having described my invention as related to the embodiment set out inthe accompanying drawings, it is my intention that the invention be notlimited by any of the details of description unless otherwise specified,but rather be construed broadly within its spirit and scope as set outin the accompanying claims.

I claim:

1. A variable speed motor, comprising: a casing, a speed governor havinga make and break switch including a pair of contact points, a transversepartition in the casing, the switch being located between the partitionand a portion of the casing containing an opening, a centrifugal fanadjacent the partition and between the partition and the switch, thepartition having an air intake opening adjacent the center of the fan,and a circular baflie on the partition adjacent the periphery of the fanand directed generally toward the switch and easing opening to directair from the fan across the switch and out this opening.

2. A variable speed motor, comprising: a casing, a speed governor havinga make and break switch including a pair of contact points, a transversepartition in the casing, the switch being located between the partitionand a portion of the casing containing an opening, a centrifugal fanadjacent the partition and between the partition and the switch, thepartition having an air intake opening therein and a circular baffle onthe partition adjacent the periphery of the fan and directed generallytoward the switch and casing opening to direct air from the fan acrossthe switch and out this opening.

3. In a variable speed motor, apparatus comprising: a casing, a speedgovernor having a make and break switch including a pair of contactpoints, a centrifugal fan in said casing, the switch being locatedbetween said fan and a portion of the casing including a ventilatingopening, and a circular baflie within the casing spaced inwardly thereofat least in substantial part, the bafiie being located adjacent to theperiphery of the fan and directed generally toward the switch and casingopening to direct air from the fan, across the switch and out the casingopening, said apparatus including a ventilating opening adjacent to thefan spaced inwardly of the bafiie and on the side of the fan opposite tothe make and break switch to supply air to said fan.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,410,361 Blackmore Mar. 21, 1922 2,092,955 Chamberlain Sept.14, 1937 2,099,050 Chamberlain Nov. 16, 1937 2,262,912 Behar Nov. 18,1941 2,292,567 Jordan Aug. 11, 1942 2,318,187 Addison, Jr. Mar. 4, 19432,388,994 Phelon Nov. 13, 1945 2,395,080 Stoller Feb. 19, 1946 FOREIGNPATENTS Number Country Date 741,175 France Dec. 2, 1932

